WO1998021444A2

WO1998021444A2 - Apparatus and method for expanding a liner patch; a stroke indicator; and a tubular patch

Info

Publication number: WO1998021444A2
Application number: PCT/GB1997/003049
Authority: WO
Inventors: Thomas Floyd Bailey; David Michael Haugen; Michael Tague Smalley; Ralph David Wright; Fredrick Thomas Tilton
Original assignee: Weatherford/Lamb, Inc.
Priority date: 1996-11-14
Filing date: 1997-11-14
Publication date: 1998-05-22
Also published as: NO20021323L; NO325410B1; EP0948703A2; NO991666D0; NO991666L; EP0948703B1; NO314511B1; CA2270986C; US5785120A; WO1998021444A3; AU4955097A; AU732007B2; NO20021323D0; CA2270986A1

Abstract

An apparatus for expanding a liner patch in a tubular to seal a hole therein, said apparatus comprising a body (134, 206, 306) having a top portion (133, 209, 309), a bottom portion (146, 229, 336) and a middle portion, the middle portion having an outer diameter greater than the top portion and an outer diameter greater than the bottom portion; a first set of fingers (135, 208, 308) disposed around the top portion of said body and a second set of fingers (156, 228, 335) disposed around the bottom portion of said body; the arrangement being such that, in use, said fingers can be urged radially outwardly by displacement thereof over said middle portion.

Description

Apparatus and Method for expanding a liner patch; a stroke indicator; and a tubular patch This invention relates to an apparatus and a method for expanding a liner patch in a tubular to seal a hole therein; a stroke indicator and a method for indicating at the earth' s surface the occurrence of a stroke during the expansion of a tubular patch; a tubular patch and a method of patching a hole.

Oil and gas wells are ordinarily completed by first cementing casing in the hole. Occasionally, a leak develops at some point in the casing and permits the loss of well fluids to a low pressure, porous zone behind the casing, or permits an unwanted fluid such as water to enter the well . It is sometimes necessary to patch a hole or other defect in oil well pipe such as casing or production tubing by expanding a malleable liner into sealing engagement with the inside wall of the pipe. Such expansion is generally achieved by the use of a special apparatus.

Accordingly there is provided an apparatus for expanding a liner patch in a tubular to seal a hole therein, the apparatus comprising a body having a top portion, a bottom portion and a middle portion, the middle portion having an outer diameter greater than the top portion and an outer diameter greater than the bottom portion; a first set of fingers disposed around the top portion of said body and a second set of fingers disposed around the bottom portion of said body; the arrangement being such that, in use, said fingers can be urged radially outwardly by displacement thereof over said middle portion.

Preferably, at least one of the fingers of said first and/or second set of fingers is releaseably connected to said body. Advantageously, at least one of said fingers comprises a tooth and said body comprises a corresponding recess which accommodates said tooth.

Preferably, the first and second set of fingers are held apart by at least one spring. Advantageously, the spring is a coil spring or a spring formed by a set of belleville washers.

Preferably, a cone is located above said body located above said body to facilitate deformation of said liner patch.

Advantageously, a sleeve is arranged about said cone and shear pinned thereto wherein, in use, said sleeve prevents said cone from entering said liner patch until said shear pin is sheared. Preferably, the apparatus further comprises a hollow piston rod, a piston and a piston cylinder wherein, in use, an increase in fluid pressure in said hollow piston rod moves said first and second sets of fingers over said middle portion. A difficulty encountered in utilizing liner patch expanding tools in casing or production tubing is in removing the tool after the tool has been driven through the liner patch. If there are restrictions in the diameter of the pipe in or above the area covered by the expanded liner patch, there is more likelihood that the tool may become jammed at the restriction and possibly even damage the liner patch or casing as it is pulled therethrough.

Advantageously, the apparatus further comprises means for retracting said first and second sets of fingers .

Preferably, the apparatus further comprises a hollow piston rod, a piston and a piston cylinder wherein, in use, an increase in fluid pressure in said hollow piston rod moves said piston whereupon said first and second sets of fingers retract.

Advantageously, the apparatus further comprises a replaceable plate in said middle portion of said body whereupon said plate may be replaced with a plate of a different thickness to vary the radial displacement of said fingers.

Preferably, said fingers comprise an external pad which, in use, engages the liner patch. Advantageously, the pad is replaceable with pads of varying thickness. Preferably, the outer diameter of the middle portion is greater than the top portion or bottom portion by more than 2.54cm (1 inch).

Advantageously, the first set of fingers are circumferentially offset with said second set of fingers .

Possibly, the apparatus comprises a first set of fingers and no second set of fingers .

The above apparatus may be lowered into the well through a small diameter tube and used in a larger diameter tubular, liner or casing.

There is also provided a method of expanding a liner patch in a tubular to seal a hole therein using the apparatus as described above.

There is also provided a method of lowering the apparatus as described above through a small diameter tube and used to expand a patch in a larger diameter tubular, liner or casing.

* * *

Often it is useful to have an indication at the surface that a casing patch system has gone through an initial stroke, e.g. in one aspect, to have an indication that the first 1.5 to 1.8m (five to six feet) of a patch has been expanded and thereby anchored in place within a tubular to be patched. The present invention also provides 18. A stroke indicator for a tubular patch expansion system for indicating that a stroke of the system has occurred, the tubular patch expansion system disposable in a tubular string in a wellbore that extends from an earth surface down into the earth, the tubular patch expansion system having an inner movable mandrel which, in use, in fluid communication with a fluid pumping system at the earth surface for pumping fluid under pressure down into the wellbore through the tubular string to the tubular patch expansion system, the stroke indicator comprising a hollow body with a bore therethrough from a top thereof to a bottom thereof, the body having at least one port therethrough in fluid communication with the bore and with space outside the body, a piston movably mounted in the body, a portion of the piston initially blocking the port to fluid flow, a connection member connectible to the movable inner mandrel of the tubular patch expansion system so that, as the movable inner mandrel moves, the connection member moves thereby moving the piston and opening the port to fluid flow, and the port positioned on the body so that the port is opened to fluid flow when a stroke of the tubular patch expansion system has occurred

* * *

The present invention also provides a wellbore tubular patch for patching a hole in a wellbore, the tubular patch having at least two connected members that, in certain aspects, are connected without welding or with minor tack welding at a rig site, the tubular patch having, in certain aspects, a top member having a corrugated body and a top end and a bottom end, a bottom member having a corrugated body and a top end and a bottom end, the bottom end of the top member inserted into and held within the top end of the bottom member. It is within the scope of this invention for more than two members to be thus interconnected. In one aspect in such a tubular patch the top end of the bottom member has a wall thickness less than a wall thickness of the corrugated body of the bottom member. In another aspect in such a tubular patch the bottom end of the top member prior to insertion into the top end of the bottom member has a wall thickness less than the wall thickness of the corrugated body of the top member and/or less than a wall thickness of the body of the bottom member. In certain aspects in such a tubular patch the top member and the bottom member are held together by holding devices or apparatuses including friction fit; tack welding; adhesive material; at least one fastener; and/or shrink fitting of one member on or in the other.

The present invention, in certain aspects, discloses a method for patching a hole in a tubular in a wellbore, the method including introducing a tubular patch system into a tubular string in a wellbore and locating it adjacent a hole in the tubular, the tubular patch system including a tubular patch having a top member having a corrugated body and a top end and a bottom end, a bottom member having a corrugated body and a top end and a bottom end, the bottom end of the top member prior to insertion into the top end of the bottom member having a wall thickness less than the wall thickness of the corrugated body of the top member, the bottom end of the top member inserted into and held within the top end of the bottom member, and expanding the tubular patch to close off the hole in the tubular. For a better understanding of the present invention and to show how the same may be carried into effect reference will now be made, by way of example, to the accompanying drawings, in which :- Fig. IA is a side view, partly in cross-section, of a prior art casing patch system;

Fig. IB-IE are side views of parts of the casing patch system of Fig. IA at various stages of operation, Fig. ID and IE being shown partly in section; Fig. IF is a side cutaway view of part of the casing. patch system of Fig. IA at a stage of operation;

Fig. IG is a top cross-sectional view of a liner patch in a casing prior to liner patch expansion;

Fig. 1H is the liner patch of Fig. IG expanded in the casing;

Fig. II is an exploded isometric view showing various parts of the casing patch system of Fig. IA.

Fig. 2 is side view, partly in cross-section of a first embodiment of an apparatus in accordance with the present invention;

Figs. 3, 4A, 4B and 5 are enlarged views of parts of the apparatus of Fig. 2 at various stages of operation;

Figs. 6A and 6B are side cross-sectional views of a second embodiment of an apparatus in accordance with the present invention in two stages of operation;

Figs. 7A and 7B are side cross-sectional views of a third embodiment of an apparatus in accordance with the present invention in two stages of operation; Figs. 8A-8C are cross-sectional views of three liner patches according to another aspect of the present invention;

Fig. 9A is a side cross-sectional view of an apparatus according to another aspect of the present invention; Fig. 9B is a view along line 9B-9B of Fig. 9A;

Figs. 9C-9D are side cross-sectional views of various stages of operation of the apparatus of Fig. 9A;

Fig. 10A is a side view, partly in cross-section of a liner patch according to the present invention;

Fig. 10B is a view on line 10B-10B of Fig. 10A;

Figs. IOC and 10D are enlarged views of parts of the liner patch of Fig. 10A; Fig. 10E is a side cross-sectional view of part of a liner patch according to another aspect of the present invention;

Figs. 10F, 10G and 10H are side cross-sectional views of a liner patch according to the present invention.

Referring to Figs. 1A-1I, there is shown a prior art casing patch system generally referred to by reference numeral 0. The casing patch system 0 includes an upper connection 1 for connection to a working string (not shown) thereabove. The working string could be a tubing string or coiled tubing. A centralizer 2, a circulating slide valve 3, a bumper jar 4, a hydraulic hold down anchor 5, a setting tool 6 including dual hydraulic cylinders 7 , 8 (each cylinder having a movable piston 9, 10 therein) , extending rod 11 which extends from a polish rod 11a which is connected at its upper end to movable piston 9, 10 in one of the dual hydraulic cylinders 7, 8 to a safety joint 12, and an expander assembly 13 that includes the safety joint 12, a cone 14, a collet assembly 15, and a lower plug 16. The liner patch 17 is made of steel and is initially located over the polish rod 11a.

As shown in Fig. IA, the liner patch 17 has been coated with an epoxy resin and the casing patch system 0 has been run into casing 18 in a wellbore (not shown) on the working string (not shown) . The liner patch 17 is positioned adjacent a leak area 19.

As shown in Fig. IB the working string is raised to close the ports 20. This is accomplished by the radially outwardly biased spring bows 21 of the centralizer 2, which maintains the slide valve 3 in relation to the casing 18 by friction therebetween. The slide valve 3 now covers ports 20.

Fig. 1C shows the effect of the application of hydraulic pressure provided by, for example a hydraulic fluid pumping system at the surface which pumps fluid down the working string and to the prior art patch system which forces radially outwardly movable buttons 22 on the hydraulic hold down anchor 5 which anchors the system 0 at the desired location in the casing 18 and isolates the working string from tensile loads associated with the setting operation.

As shown in Fig. ID, hydraulic fluid pressure on the underside of the movable pistons 9, 10 and pulls the expander assembly 13 (arrow pointing up) into the bottom of the corrugated liner patch 17. As pressure increases the expander assembly 13 is forced further into the liner patch 17 (upwardly) expanding it against the inside of the casing 18. About 1.4m (four and a half feet) of the corrugated liner patch 17 is expanded in one stroke of the setting tool 6. Then the circulating slide valve 3 is opened by lowering the working string. The working string is raised again to pull up the dual cylinders 7, 8 of the setting tool 6 in relation to pistons 9, 10 held down by the expander assembly 13. An expanded section of the liner patch 17 is anchored to the casing 18 by friction caused by compressive hoop stress. Hydraulic pressure is again applied to tubing after closing the circulating slide valve 3. Movable buttons 5 in the hydraulic hold down are expanded to anchor the cylinder in a new, higher position.

As shown in Fig. IE the expander assembly 13 is again forced through the now corrugated liner patch 17, expanding it against the inside of casing 18. This procedure is continued until the entire liner patch 17 is set. The epoxy resin coating is extruded into leaks or cavities 19 in the casing 18 and acts as a gasket and additional sealing agent. Setting time normally requires less than thirty minutes for a twenty foot liner patch 17. The tool is then removed from the hole and the liner patch 17 is pressure tested as required.

Figure IF shows a the collet assembly 15 pushing radially outwardly on the cone 14 which in turn is pushes radially outwardly on the corrugated liner patch 17 against the casing 18.

Figure IG shows a cross sectional view of the corrugated liner patch 17 in a casing 18 before deformation. Fig. 1H shows a cross sectional view of the corrugated liner patch 17 in a casing 18 after deformation.

Figure II shows various components of the system 0. Referring to Figures 2 to 4B there is shown an apparatus 100 according to the present invention. The apparatus 100 is positioned below a liner patch 101 and, in use, is located in a casing in a wellbore (not shown) . The apparatus 100 may be provided with any or all of the items used in the system 0 of Figure IA above the setting tool 6.

The apparatus 100 is provided with a cone 102 which is initially disposed in a sleeve 103. The sleeve 103 is shear pinned to a piston housing 104 by three shear pins 105. The cone 102 is provided with a shaft portion 106 which is threadedly connected to the piston housing 104 in a recess 107 therein. A shoulder 108 of the cone 102 initially rests against a shoulder 109 of the sleeve 103. The sleeve 103 has an upper end 110 which abuts the lower end 111 of the liner patch 101. The tapered end 112 of the cone 102 initially projects into the liner patch 101, although is prevented from fully entering the liner patch 101 by the sleeve 103.

The lower end 113 of the piston housing 104 is threadedly connected to an upper spring seat 114. An upper piston 115 is fast with a connecting rod 116 which is movably disposed in a channel 117 in the piston housing 104. The connecting rod 116 is connected at its upper end to a hollow extension rod (not shown) . The connecting rod 116 is provided with a flow channel 118 therethrough. The connecting rod 116 is also movable through a channel in the cone 102. Two relief ports 119 are disposed at the upper end of the piston housing 104.

The upper piston 115 is provided with an 0-ring seal 120 which acts between the upper piston 115 and the piston housing 104. The piston housing 104 is also provided with an O-ring seal 121 which acts between the connecting rod 116 and the piston housing 104. A further O-ring 122 acts between the lower end of the piston housing 104 and the upper spring seat 114. Ports 123 are provided in the upper piston 115 and an annular space 123a therearound is provided to allow fluid to flow between the flow channel 118 and the underside of the upper piston 115.

An upper piston rod 124 is connected to and depends from the upper piston 115. The upper piston rod 115 is movable in a channel 125 in the spring seat 114. A set of belleville washers 126 is arranged in an annular space 127 formed between the upper piston rod 115 and a collet sleeve 128 and below the spring seat 114. The collet sleeve 128 is threadedly connected to the upper spring seat 114. A flange 129 of a spring sleeve 130 separates the set of belleville washers 126 from a coiled spring 131 arranged therebelow. Fluid relief ports 132 are provided in the collet sleeve 128 to allow fluid to flow in and out of annular space 127.

The upper piston rod 124 passes through the upper end 133 of a collet expander 134. The coil spring 131 bears against the upper end 133. Collet fingers 135 are disposed circumferentially about the upper piston rod 124 and the upper end 133 of the collet expander 134 with gaps provided between each collet finger 135. A notch 136 is provided on the lower end of each collet finger 135 which extends radially inwardly therefrom, and locates in a corresponding detent 137 in the upper end 133 of the collet expander 134. Stress relief holes 138 are provided where the collet fingers 134 meets the collet sleeve 128. The ends of the collet fingers 135 are provided with concave portions 139.

A second set of recesses 140 are provided on the outside of collet expander 134 to accept notches 136 of the collet fingers 135.

The upper piston rod 124 is connected at its lower end to a lower piston 138 and is movably disposed in a channel 141 in the collet expander 134. Fluid relief ports 142 are disposed in collet expander 134 to allow fluid flow between the channel 141 above lower piston 138 and external to the collet expander 134. Ports 143 are provided beneath an O-ring seal 144 in the lower piston 138 and an annular space 143 therearound is provided to allow fluid flow between the channel 139 and the underside of lower piston 138.

A lower piston rod 145 is solid -and is connected to and depends from the lower piston 138 through a lower section 146 of the collet expander 134, through a coil spring 147, a spring sleeve 148 and a set of belleville washers 149 in collet sleeve 150, through a lower spring seat 151 and threadedly connected to a ball plug 152. The coil spring 147 bears against the lower end 153 of the lower section 146 of collet expander 134 and against a flange 154 of the spring sleeve 148 and against the set of belleville washers 149 which is retained in a channel 155 in the collet sleeve 148 and by the lower spring seat 151. Collet fingers 156 are disposed circumferentially about the lower piston rod 145 and the lower end 153 of the collet expander 134 , with gaps provided between each collet finger 156. A notch 157 is provided on the upper end of each collet finger 156 which extends radially inwardly therefrom, and locates in a corresponding detent 158 in the lower section 146 of the collet expander 134. Stress relief holes 159 are also provided. The ends of the collet fingers 156 are provided with convex portions 160. A second set of recesses 161 are provided on the outside of the collet expander 134 to accept notches 157 of the collet fingers 156.

In use, when it is desired to expand the liner patch 101 into position over, for example a hole in a casing, the apparatus 100 is lowered through the casing to the desired location. Fluid is pumped down the work string (not shown) through the flow channel 118, through ports 123 into chamber 117 below upper piston 115 and through ports 143 into chamber 141 below lower piston 138 (Fig. 4A, B) . Upon reaching a predetermined pressure the notches 136, 157 of the collet fingers 135, 156 move out of their respective detents 137, 158 and along the collet expander 134. The notches 136, 157 of the collet fingers finally move into the second set of recesses 140, 161 and the concave portion 139 and convex portion 160 of the collet fingers 135, 156 engage. The collet fingers 135, 156 are now in their fully expanded positions. A hydraulic hold down anchor may also be activated by the increase in fluid pressure to hold the liner patch 101 in place over the hole in the casing. An upward pull on the apparatus 100 or a further increase in pressure then shears shear pins 105 whereupon the sleeve 103 drops below the cone 102. Further upward movement of the apparatus 100 with respect to the liner patch 101 expands the liner patch 101 over the cone 102, over the piston housing 104 and finally over the collet fingers 135, 156. The collet fingers 135, 156 are pulled all of the way through the liner patch 101, or part way if the liner patch 101 is long.

Fluid pressure is then decreased upon which, the collet fingers 135, 156 move back to their original positions i.e. notches 136, 157 move back into detents 137, 158. The hydraulic hold down device is also deactivated. The apparatus 100 may then be removed or, if only part of the liner patch 101 has been expanded, the apparatus may be raised a predetermined distance for example to 3.3m (10 feet) , and fluid pressure is reapplied which activates the hydraulic hold down anchor and moves the collet fingers 135, 156 up on to the collet expander 134 as previously described.

In this particular embodiment the collet fingers 135, 156 are approximately 35cm (14 inches) long and spaced at 0.3cm (1/8 inch) intervals. A longitudinally acting force of approximately 13,350N (30001bs) is required to move such collet fingers 135 out of their corresponding detents 137, 158. The belleville springs 126 have a spring force of between 6230 N (14001bs) and 31,150 N (70001bs) , and in one aspect N (40001bs) . The coil spring 131 has a spring force of between 3,115 N (7001bs) and 11,125 N (25001bs) , and in one aspect N (15001bs) . A force of about 6,675 N (7501bs) would need to be continually applied to move the collet fingers 135 along the collet expander 134.

The apparatus 100 mainly comprises components made of steel, for example 4140 steel. The connecting rod 116, upper piston rod 124 and lower piston rod 145 may be made of 17-4 PH stainless steel. The upper and lower collet fingers 135, 156 and the collet sleeves 128, 150 may be made of 4145 steel. Although these may be made of brass, bronze, aluminium, zinc or alloys or combinations of, or of any other suitable material. The apparatus 100 may be run through a small diameter tube to patch the casing. The sleeve 103 may be sheared from the piston housing 104 by increasing fluid pressure to say 1500 psi within the tool string, and again raised to say 3500 psi to pull the collet fingers 135, 156 through the liner patch 101.

Referring now to Figures 6A and 6B there is shown an apparatus 200 according to the present invention. The apparatus 200 is positioned below a liner patch 201. The apparatus 200 may be provided with any or all of the items used in the system of Figure IA above the setting tool 6.

The apparatus 200 is provided with a cone 202 with a shaft portion 203 which is threadedly connected to a collet sleeve 204. The cone 202 initially abuts the lower end 205 of the liner patch 201. The collet expander 206 is slidably arranged within the collet sleeve 204. Notches 207 on collet fingers 208 are initially engaged in detents 209 in the upper port of the collet expander 206. A spring seat 210 is arranged inside and fixed to the collet expander 206. A channel 211 is provided through the spring seat 210. An inner piston housing 212 is connected to the cone 202 via a connector 213 and is slidably arranged in the channel 211. A coil spring 214 is arranged concentrically about the inner piston housing 212 and biases the upper surface of the spring seat 213 and the lower surface of the cone 202 apart.

An upper piston rod 215 is arranged substantially concentrically in the inner piston housing 212 providing an annular space 216 therebetween and extends from above the cone 202 to a piston 217 initially at the bottom of the inner piston housing 212. Ports 218 are disposed circumferentially about the connecting rod 215 immediately above piston 217. An O-ring seal 219 is provided in the connector 213, and another O-ring seal

220 in piston 217.

A lower piston rod 221 depends from the piston 217 and passes through a bull plug 222 and is longitudinally and rotationally locked thereto by nut 223 and shoulder 224 and a spline (not shown) . A collet sleeve 225 is threadedly connected to a shaft portion 226 of the bull plug 222. Notches 227 in collet fingers 228 are initially engaged in detents 229 in the lower part of collet expander 206. A coil spring 230 is arranged substantially concentrically about the lower piston rod

221 and biases the lower surface of the spring seat 210 and the upper surface of the bull plug 222 apart.

A removable panel 231 is located in a corresponding recess 232 in the collet expander 206. The removable panel 231 can be replaced with other panels of varying thickness so that variations in the diameter of the casing and variations in the thickness of liner patches can be catered for. A 1.2cm variance may be catered for in this embodiment. A shear pin 233 is arranged to act between the upper piston rod 215 and the inner piston housing.

In use, the apparatus 200 is lowered into the casing in an extended position, with the notches 207, 227 located in detents 209, 229. At the required point in the casing, the apparatus 200 is lifted whereupon cone 202 acts against the lower end 205 of the liner patch 201. The coil springs 214, 230 compresses at which point the notches 207, 227 jump out of detents 209, 229 allowing the collet fingers 208, 228 to expand outwardly on collet expander 206 until the collet fingers 208, 228 meet. The apparatus 200 can then be pulled through and expand the liner patch 201.

In the event that the apparatus 200 becomes stuck in the liner patch 201 or subsequently in the casing, the collet fingers 208, 228 may be retracted by increasing fluid pressure in bore 234 of the upper piston rod 215. The fluid pressure passes through ports 218 and into the annular space 216 which forces the inner piston housing 212 upwardly with respect to the piston 217, the lower piston rod 221, the bull plug 222 , and hence returning the notches 207 , 227 to their corresponding detents 209, 229. Shear pin 238 shears. The apparatus 200 may now be removed from the casing. If the apparatus 200 remains lodged in the casing, a substantial upward force applied to the upper piston rod 215 via a connector rod 235 which is connected thereto by a safety joint 235, shears a shear pin 237 arranged between the piston rod 215 and the safety joint 236. The apparatus 200 may now be "fished" from the casing using a suitable fishing tool such as an overshoot, which may engage over the top of the upper piston rod 215.

Referring now to Figures 7A and 7B there is shown an apparatus 300. The apparatus 300 is positioned below a liner patch 301. The apparatus may be provided with any or all of the items used in the system IA above the liner patch.

The apparatus 300 is provided with a cone 302 with a shaft portion 303 which is threadedly connected to a collet sleeve 304. The cone 302 initially abuts the lower end 305 of the liner patch 301 and is of greater diameter than collet sleeve 304. The collet expander 306 is slidably arranged within the collet sleeve 304. Teeth 307 on collet fingers 308 are initially engaged in detents 309 in the upper part of the collet expander 306. A spring seat 310 is fixed to an upper piston rod 311 and is slidably arranged in a channel 312 in the cone 302. The spring seat 310 is provided with a flange 313 which supports a coil spring 314 and is located in a channel 315 in the cone 302. The coil spring 314 is enclosed by a cylindrical housing 316 and an end cap 317 which retains the coil spring 314. The coil spring 314 biases the spring seat 310 and the end cap 317 apart. The upper piston rod 311 passes through a channel 318 in the end cap 317 and is slidable therethrough.

The upper piston rod 311 is connected at its lower end to a piston 319 which piston 319 is slidably arranged in an inner piston housing 320 which is slidably arranged in a channel 321 in the collet expander 306.

The upper piston rod 311 is arranged substantially concentrically in the inner piston housing 320. An annular space 322 is provided above piston 319 and below a top portion 323 of the inner piston housing 320. Ports 324 are provided to allow fluid flow between a bore 325 in the upper piston rod 311 and the annular space 322.

O-ring seals 326 and 327 are provided between piston 319 and the inner piston housing 320.

A lower piston rod 328 depends from the piston 319 and passes through a bull plug 329 and is longitudinally and rotationally locked thereto by nut 330 and shoulder 331 and a spline (not shown) . A collet sleeve 332 is threadedly connected to a shaft portion 333 of the bull plug 329. Teeth 334 on collet fingers 335 are initially engaged in detents 336 in the lower part of collet expander 306.

The coil spring 314 biases the collet fingers 308 and 335 apart.

Lugs 337 are arranged on the lower ends of collet fingers 308 and lugs 338 are arranged on the upper ends of collet fingers 335. Pads 339 and 340 are fixed to the lugs 337, 338 by screws. The pads 339, 340 project radially outwardly from the collet expander 306, initially within the external diameter of the bull plug 329 and the cone 302. The pads 339, 340 are replaceable and interchangeable with pads of varying thickness. For example, a casing with nominal 500cm (20 inch) external diameter may have an inner diameter that varies up to 1.2cm (0.466 inches) which can be accommodated for by different thickness of pads 339, 340. It should be noted that the pads 339, 340 are rounded.

In use, the apparatus 300 is lowered into the casing in an extended position, with teeth 307, 334 located in detents 309, 336. At the required point in the casing, the apparatus 300 is lifted whereupon cone 302 acts against the lower end 305 of the liner patch. The coil springs 314 compress approximately 9000Kg (20,0001bs) for 50cm (20 inch) casing at which point teeth 307, 334 jump out of detents 309, 336 allowing collet fingers 308, 335 to expand outwardly on collet expander 306 until the collet fingers 308, 335 meet. The apparatus 300 can then be pulled through and expand the liner patch 301.

In the event that the apparatus 300 becomes stuck in the liner patch 301 or in the casing, the collet fingers 308, 335 may be retracted by increasing fluid pressure in bore 325 of the upper piston rod 311. The fluid pressure passes through ports 324 and into the annular space 322 which forces the inner piston housing 316 upwardly with respect to the piston 319, the lower piston rod 328, the bull plug 329 and hence returning the teeth 307, 334 to their corresponding detents 309, 336. Shear pin 341 shears. The apparatus 300 may now be removed from the casing.

If the apparatus remains lodged a substantial upward force is applied to the upper piston rod 311 via a connector rod 342 which is connected thereto by a safety joint 343, shears a shear pin 344 arranged between the piston rod 311 and the safety joint 343. The apparatus 300 may now be fished from the casing being a suitable fishing tool such as an overshoot, which may engage over the top of the upper piston rod 311. The apparatus 300 has a large flow area around the fingers 308,335. This facilitates the ability to lower the apparatus in a small diameter tube into a large diameter tube whereupon the liner patch is expanded.

Figs . 8A-8C show top cross-section views of liner patches according to a second aspect of the present invention (which may be any desired length) . The materials may be steel, stainless steel, zinc, brass, bronze, or any suitable metal or metal alloy of any desired thickness. In one aspect the liner patches of Figs. 8A-8C are made of mild steel (e.g. 1018 steel) about 2.3mm (.089 inches) in wall thickness. They can vary in certain aspects from 1.7mm (.065 inches) to 4.8mm (.1875 inches) in wall thickness.

A liner patch 400 shown in Fig. 8A has 8 corrugations each with an angle of about 30° and at an angle of about 75° to each other. The liner patch 400 has an inner diameter of 5.4cm (2.125 inches), an outer diameter of 10.8cm (4.25 inches). Such a liner patch is suitable for sealing a hole in 16.8cm (six and five eights inch) casing; but it is within the scope of this invention to size and configure the liner patch 300 for use with any casing or tubular.

A liner patch 401 shown in Fig. 8B has 10 corrugations each with an angle of about 39° and at an angle of about 75° to each other. The liner patch 401 has an inner diameter of 6.6cm (2.6019 inches), an outer diameter of 10.8cm (4.25 inches). Such a liner patch is suitable for sealing a hole in 16.8cm (six and five eights inch) casing; but it is within the scope of this invention to size and configure the liner patch 401 for use with any casing or tubular.

A liner patch 402 shown in Fig. 8C has 10 corrugations each with an angle of about 20° and at an angle of about 55° to each other. The liner patch 402 has an inner diameter of 5.4cm (2.125 inches), an outer diameter of 10.8cm (4.25 inches). Such a liner patch is suitable for sealing a hole in 16.8cm (six and five eights inch) casing; but it is within the scope of this invention to size and configure the liner patch 402 for use with any casing or tubular.

Fig. 9A shows a stroke indicator 500 according to another aspect of the present invention useful with the apparatus 100, 200, 300 as disclosed herein. It is within the scope of this invention to use the stroke indicator with prior art patch expander systems; with any wellbore tool with an inner mandrel or member that moves with respect to an outside member or outside housing, either a mandrel/member that moves up or that moves down and with respect to which an indication of such movement at the surface is desired; with certain tools, for example, such as section mills, underreamers; casing cutters; and - with anchorable whipstocks to indicate that effective anchoring has been achieved. A top sub 501 is threadedly attached to a bottom sub 502. The top sub 501 has a body 503 through which extends a flow channel 504 and a piston channel 505. The piston channel 505 has a shoulder 506 and a port 507 is in fluid communication with the piston channel 505 and the space outside the stroke indicator 500.

A piston 510 has a portion movably mounted in the piston channel 505 of the top sub 501 and a portion movably extending down into a bore 508 of the bottom sub 502. A top piston ring 511 encircles and is threadedly connected to a top end 512 of the piston 510 (alternatively, the two parts are formed integrally together as one piece) . The ring 511 helps to retain a T-seal 541 in place.

The T-seal 541 (made, e.g., of rubber, plastic, elastomer, or any appropriate resilient seal device or material) has portions in recesses in the ring 511 and in the piston 510 and seals an interface between the piston 510 and an inner wall of the top of the piston channel 505. Alternatively, one or more O-rings or other sealing elements may be used instead of the T- seal. An O-ring 513 in the piston 510 also seals the piston channel-piston interface. In certain preferred embodiments, seal redundancy is effected so that if the T-seal fails or does not operate properly, a seal is still present between the piston and the bore wall. This is done by providing an angular mismatch between the shoulder 506 and a corresponding shoulder 539 of the piston so that a metal-to-metal seal is formed when these two surfaces contact. A lower end 514 of the piston 510 threadedly engages a threaded bore 521 in a spring sleeve 520 that is movably disposed in the bore 508- of the bottom sub 502. A hollow cylinder member 522 is connected to and extends upwardly from a shoulder 523 of the spring sleeve 520. A return spring 524 is connected at the top to a lower end of the body 503 and at the bottom to the spring sleeve 520. A lower end 525 of the spring sleeve 520 extends downwardly within a spring 526 whose top end abuts a lower surface of the shoulder 523 and whose bottom end abuts an arm 531 of a lower spring retainer 530.

The arm 531 of the retainer 530 abuts , and in one aspect seals, against a shoulder 509 blocking fluid flow, which is permitted through ports 534 until arm 431 moves up. A portion of the spring 526 encircles a top end 532 of the lower spring retainer 530. A bottom end

533 of the lower spring retainer has four ports 534

(three shown in the drawing; one, two, three or more may be used) that provide fluid communication between a bore 535 through the lower spring retainer 530 and the bore 508 of the bottom sub 502. A lower threaded end 542 of the bottom sub 502 may be threadedly mated with a patch expander system P (see Fig. 9C) which may be any system disclosed herein. In one aspect a stroke indicator 500 is used in a working string G (see Fig. 8A) , preferably positioned near an hydraulically actuated tool whose stroke or inner-mandrel/member movement is to be indicated and, with the patch expander system shown, connected to or interconnected via an extension, with the moving inner mandrel of the patch expander system.

Figs. 9A, 9C, 9D show steps in the operation of the stroke indicator 500 used with a patch expander system P. Fig. 9A shows an initial position in which a setting tool of the system P blocks fluid flow therebelow. Fluid pumped from the surface flows into the top sub 501, through the channel 505, into the bore 508, past the sleeve 520, through the bore 535 and out from the bottom sub 502 (unless another item, such as a setting tool, prevents flow from the sub 502) . At this point fluid pumped from the surface is not circulating into the wellbore or annulus outside the stroke indicator 500. The arm 531 has not moved up and compression of the spring 526 has not begun.

As shown in Fig. 9D, the patch expander system P is at the top of its stroke; some of a patch to be expanded has been expanded by the system P; the spring 526 has been compressed by the movement of the system P upwardly and the contact of the lower spring retainer by a connector C at the top of the system P. A stroke, however, has not yet been indicated by the stroke indicator 500. The lower spring retainer 530 has been moved up to contact and begin to move the spring sleeve 520 upwardly. Also, compression of the return spring 524 is commencing. As shown in Fig. 9E , the stroke indicator has been tripped and a fluid pressure reading or indication at the surface (e.g. on a pressure gauge, strip chart, or other pressure sensing/reading device) has indicated that the stroke has occurred. At this point, fluid circulation from the surface is stopped. The spring sleeve 520 has moved up; the member 522 has contacted the lower end of the body 503; and the sleeve 520 has pushed the piston 510 upwardly to such an extent that the top end 512 has cleared the bore 505 and the T-seal 541 has disengaged from the wall of the bore 505 permitting pumped fluid to exit through the port 507 into the annular space between the working string and the interior tubular wall of a tubular string including the tubular being patched. It is this fluid exit through the port 507 that produces the pressure change monitored at the surface to indicate that a stroke of the system P has occurred. As the - system P moves to effect another stroke, due to the force of the spring 524, the stroke indicator 500 is returned to the position of Fig. 9C. Then the drill string is raised (pulled up) to re-position the mandrel of the patch system for the next stroke to further expand the tubular patch. The return spring 524 (shown compressed in Fig. 9E) expands to move the spring sleeve 520 downwardly to the position of Fig. 9C as the drill string is raised and the system P releases its upward force thereby allowing expansion and release of the spring 526.

In one aspect the spring 526 has a spring force of about 1700 pounds when compressed (as in Fig. 9D) and the spring 524 has a spring force of about 35 pounds when compressed (as in Fig. 9E) . In one aspect the top sub 501 has an outer diameter of about two and one-half inches and the port 507 has an inner diameter of about three-eighths of an inch; and the bore 508 adjacent the port 507 has an inner diameter of about two and one- fourth inches. By using such springs and members with such dimensions a relatively large almost instantaneous pressure drop is achieved when fluid flows out from the port 507, facilitating a surface indication that stroke has occurred. In one particular embodiment with such springs and dimensions, the portion of the T-seal exposed to fluid pressure is sufficiently larger than that of the O-ring 513 so that the piston is "unbalanced" and the quick movement thereof is facilitated. With a relatively large spring 526, and with the mandrel of the patch system moving upwardly relatively slowly, the spring 526 is compressed, the piston top end then begins to exit the bore 505, flow past the T-seal 541 starts to commence, and the force of the spring 526 quickly pops the piston end away from the bore 505. Of course, any suitable dimensions and spring forces may be employed to produce a detectable/monitorable pumped fluid pressure difference.

It is within the scope of this invention to use a stroke indicator according to the present invention with a wellbore tool that has an inner mandrel or member that moves downwardly. In such a case the stroke indicator, e.g. as shown in Fig. 9A, would be inverted. As the tool's mandrel or inner member moves down (the mandrel connected to the lower spring retainer or to an extension connected thereto) the lower spring retainer moves down and the stroke indicator functions as previously described.

Figs. 10A-10D illustrate a tubular patch 600 including a top member 601 and a bottom member 602, each with a wall thickness "t". In one aspect the wall thickness of each member, apart from certain ends thereof, is substantially equal. In other embodiments of the present invention the wall thickness of one member differs from the other. A lower part 603 of the top member 601 has a reduced wall thickness "r" and an upper part 604 of the bottom member 602 also has such a wall thickness ^Λλr". An upper end 606 of the bottom member 602 abuts a top shoulder 605 of the top member 601. A lower end 607 of the top member 601 abuts a shoulder 608 of the bottom member 602.

As shown in Fig. 10D, the lines w, x, y, z defining the outer surfaces of the parts 603 and 604 are substantially parallel . As shown in the embodiment of Fig. 10E with a top member 601a having a lower part 603a and a top part 604a of a bottom member (not shown) . , lines m, n, o, p are not parallel. It is within the scope of this invention for the lines m and o to be at any desired angle to each other. With respect to mating end wall thicknesses, it is within the scope of this invention for the thickness of the two members to be similar or dissimilar, and for either member's end wall thickness to be thicker or thinner than the other member's end wall thickness. It is within the scope of this invention for the two members (e.g. the members 601 and 602; 601a and 602a; and 651 and 652) to be joined and secured together by any, or a combination of, the following: friction and/or press fit of parts together; welding; adhesive, e.g. but not limited to, epoxy; fasteners, e.g. but not limited to screws, pins, dowels, nails, rivets, and bolts; and heat expansion or cold contraction or one member with subsequent member connection/insertion and cooling (of a heated member) or heating (of a cooled member) to connect them together; in effect, either shrinking one member onto the other or expanding one member within the other .

Fig. 10B shows one type of patch cross-section. It is to be understood that the interconnection of two patch members taught by the present invention is applicable to patch members of any known cross-section and to any patch members disclosed herein.

Fig. 10F illustrates a tubular patch 650 (like the patch 600) that includes a top member 651 and a bottom member 652. A lower part 653 of the top member 651 has a series of teeth 659 and an upper part 654 of the bottom member 652 has a series of corresponding mating teeth 658. An upper end 656 of the bottom member 652 abuts a top shoulder 655 the top member 651. A lower end 657 of the top member 651 abuts a shoulder 660 of the bottom member 652. Upon assembly of the two members 651 and 652 together, the teeth 659 of the top member 651 ratchet past, and then interlock with, the teeth 658 of the bottom member 652 into the final position as shown.

Fig. 10G illustrates a tubular patch 670 (like the patch 600) that includes top member 671 and a bottom member 672. At an area of the top junction of the two members 671 and 672 there is an enlarged wall thickness portion 679 for added strength and an upper part 674 of the bottom part 672 is similarly enlarged. Bevelled or rounded-off edges 673 and 675 facilitate movement of the patch 670 through other tubulars and other members. The other (lower) end of the patch 670 (not shown) which is similar to that of the patch 600 (Fig. IOC) may also have similar enlarged portions for added strength.

Fig. 10H illustrates a tubular patch 680 like the patch embodiment of Fig. 10E, that includes a top member 681 and a bottom member 682; but with surfaces u and v (corresponding to lines n and o, Fig. 10E) inclined differently (as viewed in Fig. 10H) . Thus a top shoulder 683 of the bottom member 682 is larger than the top of the bottom member 602a in Fig. 10E. A similar enlarged shoulder may be used at the other end (not shown) of the junction of the top member and the bottom member.

Claims

1. An apparatus for expanding a liner patch in a tubular to seal a hole therein, said apparatus comprising a body (134,206,306) having a top portion (133,209,309), a bottom portion (146,229,336) and a middle portion, the middle portion having an outer diameter greater than the top portion and an outer diameter greater than the bottom portion; a first set of fingers (135,208,308) disposed around the top portion of said body and a second set of fingers (156,228,335) disposed around the botto portion of said body;the arrangement being such that, in use, said fingers can be urged radially outwardly by displacement thereof over said middle portion.

2. The apparatus as claimed in Claim 1, wherein at least one of the fingers of said first and/or second set of fingers is releaseably connected to said body.

3. An apparatus as claimed in in Claim 2, wherein said at least one of said fingers comprises a tooth (136,157,207,227,307,334) and said body comprises a corresponding recess (137,158,209,229,309,336) which accomodates said tooth.

4. The apparatus as claimed in any of Claims 1 , 2 or 3, wherein said first and second set of fingers are held apart by at least one spring (126,131,147,149,214,230,314) .

5. An apparatus as claimed in in Claim 4, wherein said spring is a coil spring or spring formed by a set of belleville washers.

6. The apparatus of any preceding claim, further comprising a cone (102,202,302) located above said body to facilitate deformation of said liner patch.

7. The apparatus of Claim 6, further comprising a sleeve (103) about said cone and shear pinned thereto the arrangement being such that, in use, said sleeve prevents said cone from entering said liner patch until said shear pin (105) is sheared.

8. The apparatus of any preceding claim, further comprising a hollow piston rod (116,124), a piston (115,138) and a piston cylinder (123a, 141) wherein, in use, an increase in fluid pressure in said hollow piston rod moves said first and second sets of fingers over said middle portion.

9. The apparatus of any preceding claim, further comprising means for retracting said first and second sets of fingers.

10. The apparatus of Claim 9, further comprising a hollow piston rod (215,221), a piston (217,319) and a piston cylinder (212,320) wherein, in use, an increase in fluid pressure in said hollow piston rod moves said piston whereupon said first and second sets of fingers retract.

11. The apparatus of any preceding claim, further comprising a replaceable plate (231) in said middle portion of said body whereupon said plate may be replaced with a plate of a different thickness to vary the radial displacement of said fingers.

12. An apparatus as claimed in in any preceding claim, wherein said fingers comprise an external pad (339,340) which, in use, engages the liner patch.

13. The apparatus of Claim 12, wherein said pad is replaceable with pads of varying thickness.

14. The apparatus as claimed in any preceding claim, wherein the outer diameter of the middle portion is greater than the top portion or bottom portion by more than 2.54cm (1 inch) .

15. The apparatus as claimed in any preceding claim, wherein the first set of fingers are circumferentially offset with said second set of fingers.

16. An apparatus as claimed in in any preceding claim, comprising a first set of fingers and no second set of fingers .

17. A method of expanding a liner patch in a tubular to seal a hole therein using an apparatus as claimed in any preceding claim.

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18. A stroke indicator for a tubular patch expansion system for indicating that a stroke of the system has occurred, the tubular patch expansion system disposable in a tubular string in a wellbore that extends from an earth surface down into the earth, the tubular patch expansion system having an inner movable mandrel which, in use, in fluid communication with a fluid pumping system at the earth surface for pumping fluid under pressure down into the wellbore through the tubular string to the tubular patch expansion system, the stroke indicator comprising a hollow body with a bore therethrough from a top thereof to a bottom thereof, the body having at least one port therethrough in fluid communication with the bore and with space outside the body, a piston movably mounted in the body, a portion of the piston initially blocking the port to fluid flow, a connection member connectible to the movable inner mandrel of the tubular patch expansion system so that, as the movable inner mandrel moves, the connection member moves thereby moving the piston and opening the port to fluid flow, and the port positioned on the body so that the port is opened to fluid flow when a stroke of the tubular patch expansion system has occurred.

19. A stroke indicator as claimed in Claim 18, wherein in use, opening of the port to fluid flow produces a pressure change of the fluid, the stroke indicator further comprising monitoring apparatus at the earth surface for monitoring the fluid flow and indicating the pressure change, thereby providing an indication that the stroke has occurred.

20. A stroke indicator of Claim 18 or 19, further comprising piston control means for controlling movement of the piston and for fast freeing of the piston for movement so that a quick pressure change is achieved when fluid flows out from the port.

21. A method for indicating at earth surface of a wellbore the occurrence of a stroke of a tubular patch expansion system having a stroke indicator as claimed in Claim 18, 19 or 20, said method comprising activating the tubular patch expansion system to perform a stroke of the system to expand the tubular patch, and sensing the pressure drop at the surface with pressure sensing apparatus thereby indicating that a stroke of the tubular patch expansion system has occurred.

22. A method according to Claim 21, wherein the stroke indicator further comprises piston control means for controlling movement of the piston and for fast freeing of the piston for movement so that a quick pressure change is achieved when fluid flows out from the port and the method further comprising providing an almost instantaneous pressure drop by quickly freeing the piston for movement when the stroke has occurred.

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23. A wellbore tubular patch for patching a hole in a wellbore, the tubular patch comprising a top member having a corrugated body and a top end and a bottom end, a bottom member having a corrugated body and a top end and a bottom end, and the bottom end of the top member inserted into and held within the top end of the bottom member.

24. A tubular patch of Claim 23, wherein the top end of the bottom member has a wall thickness less than the wall thickness of the bottom end thereof.

25. A tubular patch of Claim 23 or 24 , wherein the bottom end of the top member has a wall thickness less than the wall thickness of the top end thereof.

26. A tubular patch of Claim 23, 24 or 25 wherein the top member and the bottom member are held together by holding means from the group consisting of friction fit; tack welding; adhesive material; at least one fastener; corresponding mating teeth on both the top member and the bottom member; and thermal fitting of one member with respect to the other.

27. A tubular patch of Claim 23, 24, 25, or 26 further comprising an enlarged portion of the bottom end of the top member, an enlarged portion of the top end of the bottom member, and said enlarged portions strengthening a junction of the bottom end of the top member and a top end of the bottom member.

28. A method for patching a hole in a tubular in a wellbore, the method comprising locating a tubular patch as claimed in any of Claims 23 to 28 adjacent a hole in said, and expanding the tubular patch to close off the hole in said tubular.

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29. A tubular patch repair system for closing off a hole in a select tubular of a tubular string in a wellbore, the wellbore extending from an earth surface to a point down therefrom, the tubular string including a first part having a first inner diameter and a second part having a second inner diameter, the second inner diameter greater than the first inner diameter, the select tubular in the second part of the tubular string, the tubular patch repair system comprising patch repair apparatus initially sized for movement through the first part of the tubular string and enlargeable upon movement into the second part of the tubular string, the patch repair apparatus for closing off the hole in the select tubular.

30. A method for closing off a hole in a select tubular in a second part of a tubular string, the tubular string in a wellbore, the wellbore extending from an earth surface to a point down therefrom, the tubular string including a first part having a first inner diameter and a second part having a second inner diameter, the second inner diameter greater than the first inner diameter, the method comprising introducing a tubular patch repair system as claimed in Claim 29 into and through the first part of the tubular string, moving said tubular patch repair system into the second part of the tubular string, enlarging the tubular patch repair system within the second part of the tubular string for repair operation therein, and activating the tubular patch repair system to close off the hole in the select tubular.